As of October 2007, the TGM I and TGM II were merged
into a single vocabulary,
the Thesaurus for Graphic Materials, and migrated to new software. The merged
TGM is available for searching in the Prints & Photographs Online Catalog
(PPOC).

Many newspapers and magazines subscribe to the IPTC (The
International Press Telecommunications Council) standards. This was the group
responsible for the text message format developed for the teletype environment,
and still in use by many news agencies. The IPTC Subject Reference System
was developed to allow information providers access to a universal language
independant coding system for indicating the subject content of news items.
The IPTC has made their complete
set of Newscodes available
in their NewsML (XML) format that can be downloaded from this site. This
includes Descriptive Newscodes such as the IPTC
Subject, Scene and Intellectual Genre codes, which are
fields included in the IPTC Core Schema that was released in 2004.

The Proquest
list was a PDF file (weighing in at 433 pages) containing Controlled Subject
Terms for precise searching of subject fields in the Bell & Howell Information
and Learning ProQuest, CD-ROM, and licensed databases such as ABI/INFORM,
the Accounting & Tax Database, Banking Information Source, Business Dateline,
Newspaper Abstracts, Periodical Abstracts, and Resource/One. It includes
UF
(Used For), BT (Broader Topics), NT (Narrower Topics) and RT (Related Topics)
references, and would make a excellent starting point for developing your
own thesaurus if you can still find it. Previously it was located
at http://www.umi.com/hp/Support/Vocab/PDF.html, but I have been unable to
locate an update.

The Thesari of the United Nations Educational, Scientific and
Cultural Organisation, UNESCO,
includes subject terms for the following areas of knowledge: education; science;
culture; social and human sciences; information and communication; and politics,
law and economics. It also includes the names of countries and groupings of
countries: political, economic, geographic, ethnic and religious, and linguistic
groupings.

ICONCLASS
is not a controlled vocabulary, but a hierarchical list of systematically
classified definitions of subjects and themes. This collection of ready-made
definitions of objects, persons, events, situations and abstract ideas, can
be used to describe work of arts, photographs, or other visual images.

The OVID
Thesaurus web demo is designed to search more than 80 Scientific, Medical
and Technical databases including MEDLINE, Current Contents, Biosis, ABI/Inform,
PsycInfo.

Nomenclature
was a hierarchical system for the naming of artifacts, which includes a partial
lexicon, expandable by the user as appropriate. The system claims to have
a place for the name of any artifact. It appears to have been replaced by
their SPECTRUM system,
according to their staff.

The Taxonomy
Warehouse has links to approximately 73 different subject categories covering
areas from "Arts and Humanities" to "Sports and Recreation."

The JISC or Joint Information Systems Committee — which provides
free help and advice to the UK Further Education and Higher Education communities
— has a comprehensive Directory
of Metadata Vocabularies that is worth investigation.

The United States National Aeronautics and Space Administration
(NASA) has collected all of their image databases together into one portal
dubbed the NASA Image eXchange (NIX) which contains a tree form of subject
categories from which you can browse.